Paean was the physician of the gods in Greek mythology. He was mentioned in Homer's Iliad, when the god of war, Ares, was wounded by the hero Diomedes; Ares was brought to Mount Olympus, where Paean applied his knowledge and medicine to treat the wound. He also treated Hades in Homer's Odyssey, when Heracles shot an arrow against him. Paean as a god was later put aside, and the word became an epithet for Apollo, initially, and Asclepius, the god of healing, later.